EFFECTS OF RADIATION ON ENZYMES 1157 



Peroxidase activity declines upon exposure to light, as is evidenced 

 by the work of a number of investigators. Jamada and Jodlbauer (39) 

 and Zeller and Jodlbauer (94) found that peroxidase and catalase were 

 sensitive to ultra-violet and visible radiations. Visible light was active 

 only if oxygen was present, while ultra-violet was active in the absence of 

 oxygen as well as in its presence. Photodynamic substances were found 

 to speed up the inactivation in visible light. Bach (4) noted a decline 

 in its activity when exposed to sunlight in an Erlenmeyer flask. Reinle 

 (72) exposed milk to ultra-violet light and found a harmful effect on the 

 peroxidase only after prolonged exposure. Pincussen and Hammerich 

 (67s), preparing a peroxidase from the horse radish according to methods 

 described by Willstatter and Oppenheimer, found that this enzyme was 

 damaged by the light from a mercury-vapor arc. The hydrogen ion 

 concentration appeared to have little effect upon the action exerted by 

 the ultra-violet. Decrease in activity of the peroxidase was found to be 

 roughly proportional to the intensity of the light. 



Tallaricio (81) and Batelli and Stern (5) reported destruction of 

 catalase activity by sunlight, the former investigator stating that red 

 light conserves the activity while blue light decreases the activity. 

 Batelli and Stern found that the O2 factor is unimportant in the destruc- 

 tion of catalase. Waentig and Steche (91) found that the effect of light, 

 especially ultra-violet, on catalase is more pronounced in an alkaline 

 solution than in a neutral or acid one. Pincussen and Seligsohn (67/i) 

 found that blood catalase in an impure condition follows the same rules 

 that were found for other enzymes investigated by them. At pH 6 to 8 

 the inactivation of catalase by ultra-violet is a function of irradiation 

 time, as reported by Morgulis (57). Stern (79) found that irradiation of 

 liver catalase with wave-lengths of 3000 to 4000 A has no effect, but the 

 entire light of the mercury-vapor lamp retarded its activity. 



Studies on the effect of radiation on crude urease from soy bean have 

 been reported (676, 67c), but the later work of Tauber (87) was on 

 crystalline urease (after Sumner). Tauber found that direct sunhght 

 did not affect urease to which no eosin had been added at the various 

 temperatures and time intervals studied. In the presence of eosin, 

 sunlight was inactivating, while ultra-violet had an inhibitory effect upon 

 the activity inversely proportional to the distance from the radiation 

 source, and intensified by the presence of eosin. 



From the large number of experiments cited before, it may be seen 

 that in most of the studies little attempt has been made to place the work 

 entirely upon a quantitative basis. Many difficulties necessarily have 

 confronted the investigator, and the more precise earlier work, such as 

 that of Chauchard, was handicapped by the use of crude enzyme prepara- 

 tions, even though nearly monochromatic radiation was employed and 

 energies carefully measured. In a large number of the experiments, no 



